<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    

<script>
    var year =prompt('请输入年份：');
    if(year%4==0&&year%100!=0||year%400==0){
        alert('闰年！');
    }else{
        alert('平年');
    }
</script>
</body>
</html>